Implement till 3.80

ex-3_73-82.scm

@@ -108,13 +108,6 @@
 
 (display "\nex-3.78 - solve-2nd\n")
 
-; The output stream, modeling y, is generated by a network that contains a loop.
-; This is because the value of d2y/dt2 depends upon the values of y and dy/dt and
-; both of these are determined by integrating d2y/dt2. The diagram we would like
-; to encode is shown in figure 3.35. Write a procedure solve-2nd that takes as
-; arguments the constants a, b, and dt and the initial values y0 and dy0 for y
-; and dy/dt and generates the stream of successive values of y.
-
 (define (solve-2nd a b dt y0 dy0)
   (define y (integral (delay dy) y0 dt))
   (define dy (integral (delay ddy) dy0 dt))
@@ -130,9 +123,32 @@
         0.5000141490501059) ; sin pi/6 = 0.5
 
 (display "\nex-3.79 - solve-2nd-general\n")
+(display "[ok]\n")
 
-(define (solve-2nd-general a b) '())
+(define (solve-2nd-general f y0 dy0 dt)
+  (define y (integral (delay dy) y0 dt))
+  (define dy (integral (delay ddy) dy0 dt))
+  (define ddy (stream-map f dy y))
+  y)
+
+(display "\nex-3.80 - RLC\n")
+
+(define (RLC R L C dt)
+  (define (rlc-proc vC0 iL0)
+    (define vC (integral (delay dvC) vC0 dt))
+    (define iL (integral (delay diL) iL0 dt))
+    (define dvC (scale-stream il (/ -1 C)))
+    (define diL
+      (add-streams
+        (scale-stream iL (/ (- R) L))
+        (scale-stream vC (/ 1 L))))
+    (cons vC iL))
+  rlc-proc)
+
+(define RLC1 (RLC 1 1 0.2 0.1))
+(display "[ok]\n")
+
+(display "\nex-3.81\n")
+
+(display "\nex-3.82\n")
 
-;(display "\nex-3.80\n")
-;(display "\nex-3.81\n")
-;(display "\nex-3.82\n")